High-Yield Neuroanatomy 5e

Glossary 181
results in a small change in pupil size bilaterally,
and light shone into the normal pupil results in a
decrease in pupil size in both eyes.
sympathetic apraxia Motor apraxia in the left hand;
seen in lesions of the dominant frontal lobe.
syringomyelia Cavitation of the cervical spinal cord
results in bilateral loss of pain and temperature
sensation and wasting of the intrinsic muscles of
the hands. Syringes may be found in the medulla
(syringobulbia) and pons (syringopontia) and in
Arnold-Chiari malformation.
tabes dorsalis Locomotor ataxia; progressive demyelination
and sclerosis of the posterior columns and
roots; seen in neurosyphilis.
tactile agnosia Inability to recognize objects by touch.
tardive dyskinesia Syndrome of repetitive, choreoathetoid
movements frequently affecting the face;
results from treatment with antipsychotic agents.
Tay-Sachs disease (GM 2
gangliosidosis) Best-known
inherited metabolic disease of the central nervous
system (CNS); characterized by motor seizures, dementia,
and blindness; a cherry-red spot (macula)
occurs in 90% of cases; caused by a deficiency of
hexosaminidase A; affects Ashkenazi Jews.
tethered cord syndrome (filum terminale syndrome)
Characterized by numbness of the legs and feet, foot
drop, loss of bladder control, and impotence.
thrombus Clot in an artery that is formed from blood
constituents; gives rise to an embolus.
tic douloureux Trigeminal neuralgia.
tinnitus Ringing in the ear(s); seen with irritative lesions
of the cochlear nerve (e.g., acoustic neuroma).
titubation A head tremor in the anteroposterior direction,
often accompanying midline cerebellar lesions;
also a staggering gait.
tremor Involuntary, rhythmic, oscillatory movement.
tuberous sclerosis (Bourneville disease) Neurocutaneous
disorder characterized by the trilogy of mental
retardation, seizures, and adenoma sebaceum.
Cutaneous lesions include periungual fibromas,
shagreen patches, and ash-leaf spots.
uncinate fit Form of psychomotor epilepsy, including
hallucinations of smell and taste; results from lesions
of the parahippocampal gyrus (uncus).
upper motor neurons (UMNs) Cortical neurons that
give rise to the corticospinal and corticonuclear
tracts. Destruction of UMNs or their axons results
in a spastic paresis. Some authorities include brain
stem neurons that synapse on lower motor neurons
(LMNs) (i.e., neurons from the red nucleus).
vertigo Sensation of whirling motion due to vestibular
disease.
visual agnosia Inability to recognize objects by sight.
von Hippel-Lindau disease Disorder characterized
by lesions of the retina and cerebellum; retinal
and cerebellar hemangioblastomas. Non–central
nervous system (CNS) lesions may include renal,
epididymal, and pancreatic cysts, as well as renal
carcinoma.
Wallenberg’s syndrome Condition characterized by
hoarseness, cerebellar ataxia, anesthesia of the ipsilateral
face and contralateral body, and cranial
nerve signs of dysarthria, dysphagia, dysphonia,
vertigo, and nystagmus; results from infarction of
the lateral medulla due to occlusion of the vertebral
artery or its major branch, the posterior inferior
cerebellar artery (PICA); Horner’s syndrome is
frequently found on the ipsilateral side.
Wallerian degeneration Anterograde degeneration of
an axon and its myelin sheath after axonal transection.
Weber’s syndrome Lesion of the midbrain basis pedunculi
involving the root fibers of the oculomotor
nerve and the corticobulbar and cortospinal tracts.
Werdnig-Hoffman syndrome (spinal muscular atrophy)
Early childhood disease of the anterior horn
cells [lower motor neuron (LMN) disease].
Wernicke’s aphasia Difficulty in comprehending
spoken language; also called receptive, posterior,
sensory, or fluent aphasia.
witzelsucht Inappropriate facetiousness and silly joking;
seen with frontal lobe lesions.